Slot nozzles of the afore-mentioned type serve for the areal application of different types of flowable material to various types of surfaces. Depending upon the intended purpose, e.g. dissolved or reactive synthetic resins such as polyurethane may be used as the material to be applied, but cold glue or hot-melt adhesive are also suitable. Such materials may for instance be applied for coating purposes to narrow surfaces of wood, plastic or metal profiles or as adhesive strips to films or paper surfaces.
For all applications, there is often the problem that the width in which the flowable material is to be applied varies, for instance because wood or plastic profiles of different thicknesses are to be coated, or because adhesive or color strips are to be applied in varying widths, for instance to film surfaces. Slot nozzles, the dispensing width of which is changeable, are known for such applications. It goes without saying that such slot nozzles must also be easy to dismantle and assemble and to be free of residues of adhesive or synthetic resin for cleaning purposes. In order that for instance, reactive resin does not remain in "dead water areas" of the slot nozzle until it hardens, as far as possible material should flow constantly through all channels of the slot nozzle while in use; this also applies to those channels or parts thereof which are temporarily not required when the slot width is reduced.
The requirement for dismantling ability of the slot nozzle yields the problem of imperviousness at the parting surfaces. Due to the different types of materials which are to be applied, it must first be expected that these are of low viscosity and capable of creep; however it may also be that the materials contain solvents which will attack the seals of the slot nozzle. Finally, there are a number of fields of application where what matters is that the slot nozzle is flat. Such a field of application is for instance, the gluing of edge veneers to the lateral surfaces of table leaves and the like. Often the edge veneers can be supplied to the lateral surfaces only at an obtuse angle because they break easily owing to their brittleness if the bending radius is too small when applying the edge veneer to the lateral surface to be veneered. At the same time, the adhesive should be applied as immediately as possible in the vicinity of the point at which the edge veneer and the lateral surface meet, because then fast-hardening adhesives can be used for a high production rate without there being the risk of the adhesive hardening even before the edge veneer and the lateral surface have met. Precisely when veneering the lateral surfaces of table leaves, due to the different thicknesses of the table leaves, the problem often occurs that the width of the adhesive film has to be matched to this thickness.
The object underlying the invention therefore consists in devising a slot nozzle which can be used as universally as possible, which avoids the problems discussed previously to as great an extent as possible and meets the requirements stated and is as simple as possible in construction.